Currently, metrics configuration uses a black-listing approach with a tags system. Since enabling more and more metrics increases cluster resource usage, it would be better to switch to a white-listing approach, where user only select what they need.

This is also safer during upgrades, when users already have this setting configured explictly, since in that case the new default won't apply and, with black-listing, new metrics could be automatically enabled without the user noticing.

On top of that, it's confusing to have overlap between tags. 

We should think about more explicit tags (including 'all' mention like 'all_namespaces', or forcing fully qualified names like 'ingress_namespaces_packets')

NOTE FOR QE

You can read the release note text for the user facing changes. One special thing to test will be the upgrade scenario, especially after we add new metrics (such as RTT, drops... e.g. https://github.com/netobserv/network-observability-operator/pull/408) => we need to make sure there isn't any unintended metric generated beyond the defaults. This is kind of a chicken-egg problem as these PRs are bocked by this one, so this particluar thing will have to be tested after both are merged.